What I meant was are you still gonna connect the J2 (labelled MBON# and MBON2# on the circuit diagram) on the ITPS into the PC motherboard?
Ok my fault I didnt ask the question properly...my plan was just to apply the power to your motherboard when turning on and then cut the power when turning off. The ITPS will not do anything else, it just toggle the power on and off to your motherboard controlled by the push button. I got an impression this is what you wanted since you wanted on and off with no delay...it didnt make sense that you wanted this
Some people do this, hard on and off and no proper shutdown. If this is the case then I have done it already.
If you do want the sequence like this :
YOU push BUTTON and release - YOU want the PC to bootup
ITPS turn power rail on - ITPS apply battery power to the PC
ITPS wait 1 sec - ITPS wait for PC to settle down on receiving battery power
ITPS trigger PCBUTTON - ITPS bootup the PC
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.
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YOU push BUTTON again and release - YOU want PC to shutdown
ITPS trigger PCBUTTON - ITPS shutdown the PC
ITPS wait 45 sec - ITPS wait for PC to shutdown
ITPS turn power rail off - ITPS remove battery power to the PC
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ITPS repeat cycle
For the PC to work properly ITPS must apply the battery power to the PC 1 second atleast before ITPS push the PCBUTTON. I think we are getting confused with the PC powering on/off with the battery power into the PC...they are different things

And also with the push BUTTON and the PC power BUTTON.
BUTTON = your push button
PCBUTTON = pc power button
12V = power going into the PC
PC powering up should be called PC booting up
I hope thats clearer